The goal is a software Speech Perception Assessment and Training System (SPATS) for the aural rehabilitation of adult hearing aid and cochlear-implant users. The system will assess the user's ability to identify the constituents of English syllables; that is, syllable onsets, nuclei, and codas in quiet and in background noise, and it will provide individualized recognition training to improve these abilities. An administrative component of the system will keep and report records and simplify navigation of the system by clinicians and clients. Three parts of the project are: 1) the development of the assessment components of the system, 2) the development of the training components of the system, and 3) their clinical validation. Assessments will provide an inventory of a client's abilities to identify the constituents of English syllables. Including variation in talkers, phonetic contexts, and noise levels assures that the assessments are valid and objective evaluations of a listener's bottom-up, or analytic, speech-perception abilities. The training algorithm adaptively selects items and noise levels so that practice is concentrated on items of moderate difficulty weighted by their importance for speech understanding. Item importance is estimated from frequency of occurrence data. Further, learning is enhanced by providing many practice trials, immediate feedback, and, following errors, rapid comparisons of intended sounds with their confusors and by including both relatively easy, low-uncertainty and more difficult, high-uncertainty conditions. To better motivate the user and to encourage transfer to real-world speech, briefer periods of training on words and phrases will be regularly interspersed with the training on syllable constituents. Validation studies will measure how well the assessment system predicts success in identifying words and sentences, and general success in speech communication. Correlations with subjective estimates of benefit from, satisfaction with, and use of hearing aids and cochlear implants in relation to the proposed assessment tools will also be measured. Assessment components of the system will be suitable for patient evaluation and for the evaluation of the performance of hearing-aids and their fittings as well as for the evaluation of the performance of cochlear implants, maps, programs, and processing schemes. The effectiveness of the training system for improving the validation measures and, thus, the clients' overall ability to understand speech, will be measured. The training components of the system can be used in aural rehabilitation programs in clinical settings and in the home.